Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, issued
Preferred stock, outstanding
Common stock, par value	$ 0.0005	$ 0.0005
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	156,234,415	156,234,415
Treasury stock, shares	62,815,971	62,891,251